Crystallization Behavior of Isotactic Propylene-1-Hexene Random Copolymer Investigated by Time-Resolved SAXS/WAXD Techniques

Journal Article · Fri Jan 01 04:00:00 EST 2010 · Journal of Polymer Science Part B: Polymer Physics

DOI:https://doi.org/10.1002/polb.21840· OSTI ID:1019947

Mao, Y; Zuo, F; Keum, J; Hsiao, B; Thurman, D; Tsou, A

The crystallization behavior of isotactic propylene-1-hexene (PH) random copolymer having 5.7% mole fraction of hexene content was investigated using simultaneous time-resolved small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) techniques. For this copolymer, the hexene component cannot be incorporated into the unit cell structure of isotactic polypropylene (iPP). Only {alpha}-phase crystal form of iPP was observed when samples were melt crystallized at temperatures of 40 C, 60 C, 80 C, and 100 C. Comprehensive analysis of SAXS and WAXD profiles indicated that the crystalline morphology is correlated with crystallization temperature. At high temperatures (e.g., 100 C) the dominant morphology is the lamellar structure; while at low temperatures (e.g., 40 C) only highly disordered small crystal blocks can be formed. These morphologies are kinetically controlled. Under a small degree of supercooling (the corresponding iPP crystallization rate is slow), a segmental segregation between iPP and hexene components probably takes place, leading to the formation of iPP lamellar crystals with a higher degree of order. In contrast, under a large degree of supercooling (the corresponding iPP crystallization rate is fast), defective small crystal blocks are favored due to the large thermodynamic driving force and low chain mobility.

• Research Organization: Brookhaven National Laboratory (BNL) National Synchrotron Light Source
• Sponsoring Organization: DOE - OFFICE OF SCIENCE
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 1019947
• Report Number(s): BNL--95793-2011-JA
• Journal Information: Journal of Polymer Science Part B: Polymer Physics, Journal Name: Journal of Polymer Science Part B: Polymer Physics Journal Issue: 1 Vol. 48; ISSN 0887-6266
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CHAINS
COPOLYMERS
CRYSTALLIZATION
HEXENES
MORPHOLOGY
POLYPROPYLENE
SCATTERING
SEGREGATION
SUPERCOOLING
THERMODYNAMICS
X-RAY DIFFRACTION
national synchrotron light source